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Police forces across the UK effectively campaigned to use a face scanning system known to be discriminatory against females, young people, and members of ethnic minority groups, following complaints that a less biased version generated fewer investigative leads.

How the System Works

UK forces utilize the national police database to conduct retrospective facial recognition searches. This process entails comparing a reference photograph of a person of interest against a database of over 19 million mugshots to identify potential matches.

Acknowledged Discrimination

The UK interior ministry conceded last week that the technology was biased. This acknowledgment came after a study by the government's National Physical Laboratory found it incorrectly matched Black and Asian people and females at significantly higher rates than Caucasian males. The Home Office said it “had acted on the findings”.

“It prompts the question of whether facial recognition only becomes useful if users accept discrimination in race and gender. Operational ease is a weak argument for overriding fundamental rights.”

Known Issue

Internal documents reveal that this bias has been known about for over twelve months. Furthermore, law enforcement lobbied to reverse an initial decision that was designed to mitigate the problem.

Police bosses were notified of the algorithmic discrimination in late 2024. The Home Office-commissioned laboratory study found the system was had a higher probability to suggest incorrect matches for images depicting women, individuals of Black ethnicity, and those aged 40 and under.

A Reversed Decision

In reaction, the National Police Chiefs’ Council (NPCC) ordered that the confidence threshold required for potential matches be increased to a level where the bias was greatly diminished.

However, this directive was reversed the following month after forces complained that the modified technology was generating fewer “useful lines of inquiry”. NPCC documents show the stricter setting cut the proportion of queries resulting in possible identifications from over half to a just under 15%.

Severe Disparities

Although the authorities refused to say what setting is currently used, the latest independent review found the system could generate incorrect matches for Black women nearly a hundred times more often than for Caucasian women at certain settings.

The ministry stated on these results: “Our evaluation found that in a limited set of circumstances the software is has a greater tendency to wrongly flag some demographic groups in its search results.”

Balancing Utility and Fairness

Outlining the effect of the brief increase to the system's accuracy setting, the NPCC documents state: “This adjustment significantly reduces the impact of bias across protected characteristics of race, generation and sex but had a substantially detrimental effect on police efficiency”. The papers add that police units argued that “a previously useful tool returned outcomes of limited benefit”.

Broader Rollout Plans

Meanwhile, the government has launched a ten-week consultation on its plans to expand the use of biometric scanning systems. The minister for police the relevant minister has described the technology as the “biggest breakthrough since DNA matching”.

Expert and Oversight Concerns

The chair of a police oversight board, chair of the advisory panel for the national policing equality strategy, commented: “We observed scant discussion in equality strategy sessions of the technology deployment even with clear relevance with the strategy's goals.

“This disclosure show yet again that the pledges to combat discrimination the police has made via the race action plan are failing to be integrated into broader operations. Independent assessments have warned that innovative tools are being implemented in a context where racial disparities, inadequate oversight and poor data collection already persist.

“Any use of facial recognition must meet rigorous official guidelines, be subject to external review, and demonstrate it diminishes rather than exacerbates ethnic bias.”

Official Statement

A government representative stated: “The Home Office takes the findings of the study with utmost gravity and we have implemented changes. A updated software has been independently tested and procured, which has no statistically significant bias. It will be tested early next year and will be undergo evaluation.

“Our priority is protecting the public. This gamechanging technology will assist police to apprehend and prosecute offenders. There is officer review in each stage of the process and no arrest or charge would be taken without trained officers meticulously examining the output.”